.. code-block:: python

	#!/usr/bin/env python
	
	import pymzml
	from collections import defaultdict as ddict
	import os
	
	
	def main():
	    """
	    Testscript to isolate the n-highest peaks from an example file.
	
	    Usage:
	
	        ./highest_peaks.py
	
	    Parses the file '../tests/data/example.mzML' and extracts the 2 highest
	    intensities from each spectrum.
	
	    """
	    example_file = os.path.join(
	        os.path.dirname(__file__),
	        os.pardir,
	        'tests',
	        'data',
	        'example.mzML'
	    )
	    run = pymzml.run.Reader(
	        example_file
	    )
	    highest_i_dict = ddict(list)
	
	    number_of_peaks_to_extract = 2
	
	    for spectrum in run:
	        # print( spectrum.ID )
	        if spectrum.ms_level == 1:
	            for mz, i in spectrum.highest_peaks(number_of_peaks_to_extract):
	                highest_i_dict[ spectrum.ID ].append(i)
	    for spectrum_id, highest_peak_list in highest_i_dict.items():
	        assert len(highest_peak_list) == number_of_peaks_to_extract
	        print(
	            'Spectrum {0}; highest intensities: {1}'.format(
	                spectrum_id,
	                highest_peak_list
	            )
	        )
	
	
	if __name__ == '__main__':
	    main()
